Ike came ashore in Galveston, Texas, early Saturday morning as a Category 2 storm with maximum sustained winds of 110 mph. Storm surge was about 10 feet, much less than the predicted range of 20 – 25 feet. Even so the storm caused extensive flooding throughout the Galveston – Houston area, and hurricane-force winds were felt well inland for several hours following landfall.

One of the key conclusions was the need for stronger mooring systems that anchor rigs to the sea floor, sometimes in thousands of feet of water. That’s prompted major rig owners like Transocean Inc. and Noble Drilling Inc. to increase the number of anchor lines from eight or nine to 12 in some cases.

One of Transocean’s moored rigs, the Marianas, broke free during Hurricane Rita in September 2005 and drifted 140 miles (225 kilometers). Another, the Deepwater Nautilus, was set adrift a month earlier by Katrina.

Such unscheduled voyages can be costly. Besides lost revenue, Transocean spent $25 million (euro19 million) to fix and upgrade the two rigs, both of which now have 12-point mooring systems.

Katrina and Rita were Cat 5 monsters in the Gulf with sustained winds reaching 175 mph. But another of Transocean’s mobile rigs, the Amirante, suffered damage to its mooring system from the relatively weak Hurricane Gustav and was towed back to port for repairs. Ike’s winds (110 mph) were weaker than Gustav’s (115 mph). It’s only a matter of time before the Gulf will experience another major Category 4 or 5 hurricane. Maybe those mooring systems need another serious look. I’ll bet the companies that insure those rigs will insist.

Check out the discussion on The Oil Drum blog if you want to learn more.

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